In the context of computer programming, a user interface of a software program is where interactions between a human user of the program and the program occur. Typically, the user interface of a program may include various components, such as windows, panels, menu bars, menus, menu items, buttons, text fields, check boxes, dialogs, etc., and particular user-interface components may be arranged according to specific designs suitable to the requirements, specification, or functionalities of the program. The user interface, via individual user-interface components, enables the human user to provide input to the program (e.g., entering text in a text field, selecting a menu item, or clicking a button), and displays the output of the program to the human user (e.g., showing a message in a dialog, or playing a video clip in a media panel).
Both web-based and standalone software applications may and usually do have user interfaces. A web-based application is a software application that is executed within a web browser (including browsers suitable for computers and mobile devices). Typically, a web-based application may be associated with a unique Uniform Resource Identifier (URI), such as in the form of a Uniform Resource Locator (URL). To invoke a web-based application, a user may input the URL of the web-based application in a web browser. For example, a social networking website, such as the one provided by Facebook®, may provide a web-based application that enables its users to stay in touch with their friends and families, play Internet games, and managing personal schedules. In this case, to invoke the web-based application, a user may input the URL “www.facebook.com” in a web browser executing on a network device (e.g., a computer or a mobile telephone). The user interface of the application includes a set of web pages that may be individually displayed in the user's web browser. For example, upon invoking the application, initially, a login/sign up page may be presented to the user so that the user may either log into his existing account or sign up for a new account. Once the user has successfully logged in, a welcome page (e.g., the home page of the user's account) may be presented to the user from where the user may perform other activities and interact with the application (e.g., communicating with friends, uploading photos, playing Internet games, or managing the user's profile).